Electrostatic discharge (ESD) is the sudden and momentary electric current between two objects at different electrical potentials. A common cause of ESD events is static electricity from humans who contact an object which is at a different electric potential or equipments that collect charge during operation. Such ESD events can permanently damage integrated circuit (IC) chips if they are not protected by ESD protection circuitry.
High-level electrostatic discharge (ESD) stress protection typically requires a large area for the protection device on the product layout. For high-speed circuits that cannot tolerate large capacitive loading, alternative techniques are required. Further, as the reduction of device dimensions in advanced deep sub-micron process technologies make them more sensitive to the ESD-stress, function of ESD protection becomes more challenging.